Struthionidae is a family of flightless ratite birds which first appeared during the Eocene epoch. It is today represented by the sole living genus Struthio, but also contains several extinct genera.[2] Traditionally the order Struthioniformes contain the world's ratites, but recent genetic analysis has found that the group is not monophletyic, as it paraphyletic in respect to the tinamous.[3][4]